Polyarylene sulfide (hereinafter abbreviated as “PAS”) resin, represented by polyphenylene sulfide (hereinafter abbreviated as “PPS”) resin, is excellent in heat resistance, mechanical properties, chemical resistance, dimensional stability, and flame resistance. Therefore, the PAS resin has been widely used as a material for parts of electrical or electronic devices, a material for parts of vehicle devices, a material for parts of chemical devices, etc., in particular for applications under high temperatures in usage environment.
Considerable percentage of the PAS resin-containing molded articles utilized in a variety of fields as mentioned above is accounted for by those made by insert molding. The insert molding method is a molding method in which metals or inorganic solids and the like (hereinafter, occasionally abbreviated as “metals and the like”) are embedded in resins while making the most of the properties of the resins and the material properties of the metals and the like.
The resins and the metals and the like differ extremely in their rates of expansion or contraction due to temperature change (so-called coefficient of linear thermal expansion). As a result, if a resin portion of the molded articles is thin, the molded article frequently cracks due to the temperature change immediately after the molding or during use, especially in the case where the metals and the like have a sharp corner, and the like.
Recently, resins have also been employed in components located around an engine of vehicles. Since the temperature change is large around the engine of the vehicles, resin compositions having more excellent high- and low-temperature impact property are required.
As a resin composition possessing superior high- and low-temperature impact property, there are known a resin composition in which an olefin-derived copolymer containing an α-olefin and a glycidyl ester of an α,β-unsaturated acid as major components is incorporated into the PAS resin (see, Japanese Unexamined Patent Application, Publication No. 2000-263586), and a resin composition in which an olefin-derived copolymer of ethylene and an α-olefin of at least 5 carbons is incorporated into the PAS resin (see, Japanese Unexamined Patent Application, Publication No. 2002-179914).
When the resin composition described in Japanese Unexamined Patent Application, Publication No. 2000-263586 or 2002-179914 is employed, the high- and low-temperature impact property is improved. However, thermoplastic elastomers including the above-mentioned olefin-derived copolymers are subject to thermal deterioration at elevated temperatures. As result of this drawback, the improvement strategy of the incorporation of the elastomers as described in Japanese Unexamined Patent Application, Publication Nos. 2000-263586 and 2002-179914 gives rise to another problem that a mold deposit (MD) remarkably increases during the molding. Herein, the mold deposit refers to substances adhered to a mold during the molding.
As a method to solve the problem of the mold deposit while allowing the resin composition to retain sufficient high- and low-temperature impact property, there are known a method in which a specific anti oxidant is further incorporated into a PAS resin and a specialized olefin-derived copolymer (see, Japanese Unexamined Patent Application, Publication No. H10-279802), and a method in which a specialized olefin-derived copolymer is incorporated into a PAS resin (see, Japanese Unexamined Patent Application, Publication No. 2006-1955).
[Patent Document 1] Japanese Unexamined Patent Application, Publication No. 2000-263586
[Patent Document 2] Japanese Unexamined Patent Application, Publication No. 2002-179914
[Patent Document 3] Japanese Unexamined Patent Application, Publication No. H10-279802
[Patent Document 4] Japanese Unexamined Patent Application, Publication No. 2006-1955